title: Serum derived from zeranol-implanted ACI rats promotes the growth of human breast cancer cells in vitro.
abstract: BACKGROUND
  Zeranol (Z) is a non-steroidal anabolic growth promoter with potent estrogenic activity that is widely used as a growth promoter in the US beef industry. Consumption of beef derived from zeranol-implanted cattle may be a risk factor for breast cancer.
  
  
  METHODS
  The effect of serum on the proliferation of human breast cancer MCF-7 cell line and primary cultured human breast epithelial cells (PCHBECs) was investigated. ACI rats were implanted with 12 mg zeranol pellet and the serum was harvested at day 110 after implantation. The effect of zeranol-serum on mRNA expression of cell cycle regulating gene (cyclin D1) and tumor suppressor genes (p53, and p21) was evaluated using real-time RT-PCR.
  
  
  RESULTS
  The serum derived from ACI rats 110 days post-zeranol implantation significantly promoted the proliferation of MCF-7 cells and primary cultured human breast epithelial cells compared to control serum. Zeranol-serum up-regulated cyclin D1 and down-regulated p53 and p21 expression in PCHBECs compared with control serum.
  
  
  CONCLUSIONS
  Bio-active zeranol metabolites contained in meat produced from cattle after zeranol implantation may be a risk factor for breast cancer.
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
authors.forename: Saiyi
authors.initials: S
authors.lastname: Zhong
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Ye
authors.forename: Eric
authors.initials: E
authors.lastname: Feng
authors.forename: Shu-Hong
authors.initials: SH
authors.lastname: Lin
authors.forename: Jie-Yu
authors.initials: JY
authors.lastname: Liu
authors.forename: John
authors.initials: J
authors.lastname: Leong
authors.forename: Changwei
authors.initials: C
authors.lastname: Ma
authors.forename: Young C
authors.initials: YC
authors.lastname: Lin
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis / Q000235:genetics; D004968:Estrogens, Non-Steroidal / Q000097:blood*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D011912:Rats, Inbred ACI; D044967:Serum; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics; D015029:Zeranol / Q000097:blood*
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D004968:Estrogens, Non-Steroidal; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D019938:Cyclin D1; D015029:Zeranol